Where And When To Use Shielded Ethernet Cable?

We’ve got an unshielded and shielded Ethernet cable as below. So obviously what draws your eyes immediately is that these are both Cat5e cables.

The shielded Ethernet cable is typically going to be thicker than unshielded. And with unshielded cable, the construction is very simple. We’re talking about Cat5e, so there’s no internal spline. But otherwise, this is going to be pretty much the same as any other whether it’s Cat6 or Cat6a.  You’ll have a ripcord in the cable and you’ll have these four pairs of eight wires twisted into blue, orange, brown, and green, the pair twists do impart a bit of electromagnetic shielding to the cable and so does the cable jacket. So to call this unshielded cable is a bit of a misnomer because Ethernet cable is by definition a kind of self-shielding. After all, these conductors cancel each other or cancel electromagnetic fields out. So as long as they’re not overwhelmed, this will function just fine in the vast majority of environments. When you do run across that environment that unshielded is just not suitable for, well, that’s going to leave you with shielded cable.

And So shielded Ethernet cable the first thing you’re going to notice besides the thickness is that there’s a bluish, mylar-backed foil shield, and there’s the rip cord right here so we’re going to kind of peel this back and see what’s inside. Once you peel back this coil shield, you’re going to notice that there’s also a tinned copper drain wire. This drain wire makes contact what the inside of the cable shield along its length. And this serves primarily as the ESD drain ground and then the shield is bonded with this wire so a bonded means it’s making a low impedance electrical contact. So typically, you’ll use the drain wire and shield in combination when bonding termination hardware. You can also remove the cable shield and then just simply use the drain wire with some copper tape, copper fabric tape stuff like that. So in the case of the shielded Ethernet cable, it may have some additional dielectric wraps like this. When I mean dielectric, I mean non-conducting. And that is designed to keep the conductors from actually touching the metal of the shield itself and then you’ll have your typical four pairs which we had on the other cable so we got our we got our orange, green, blue, and brown.

What does the cable shield do? Cable shielding prevents the internal pairs from being overwhelmed by what’s called alien crosstalk. This can be interference from another shielded Ethernet cable, but more likely it’s interference from electromagnetic fields, such as AC wiring inside a wall. If you can’t maintain an eight-inch distance, or if you’re running your cabling near powerful electrical motors, or if you have radio frequency issues in your area, like living under high voltage power lines, shielding becomes important. However, shielded Ethernet cable by itself does not increase performance over unshielded cable. Therefore, only use a shielded Ethernet cable when you know you need it and are looking to avoid a specific problem. There are additional considerations that come with using shielded Ethernet cable, such as bonding the cable shield to the ground; otherwise, the shield won’t be effective. To best avoid electrical interference, plan your installation by using distance as a primary strategy.